2021 Peterbilt with a CM2450 with error code 1696

[Luckyjayb]

Working on a dump truck that had a bad demandate in it and had it fixed by one of the members on here. Before and after the fix, I was getting error code 1696, supply signal 5 low voltage or short to ground. The previous guy that put on the horrendous demandate, cut the wires at the ecm plug and throttle pedal and ran wires that was. Nothing ohm’d out right so I had to put a new oem harness from the ecm to firewall and other connections. I tried to make the original connection at the connector for the throttle by soldering and heatshrink. It worked fine for a few days then went back to acting up. While looking at live data on insite, it shows a constant 5 volts. When looking at it on Calterm 3, it will drop down to .2 to .3 bolts when it looses pedal. I’ve disconnected, one at a time, all connectors in signal supply 5 and the pedal is the only issue. It will idle up all day long, but as soon as it is in gear, it’s an Allison automatic 4500 RDS transmission, it starts to act up. The voltage and ohm’d check out fine at idle and with the truck off. Truck only has 80k on the odometer. I’m at a loss on it and I know I’ve got at least 30 hours in electrical troubleshooting on this issue. Anybody have any ideas or suggestions on the next step. Trying to save the customer a harness behind the dash. The last time it went out on the driver, he hit a deep pothole at a slow speed. Thanks in advance

[Rawze]

In the programming, it shows 'supply signal 5' on the CM2450's is tied to ...

* DPF Delta-P sensor.

* DPF Outles pressure sensor.

* Def Pump Pressure sensor.

* Accelerator Pedal (signal #2).

* Coolant Level sensor.

* fuel Level Sensor.

* Remote accelerator pedal (if it has one).

* DEF Pressure Sensor (an optional one).


====

and just because it might be demandated, does not mean it cannot throw a fault for any of those circuits .. as the power feed supply is tied to all of them together. The ecm will not know exactly what sensor it is, but only there is a fault with that power feed .. and it resorts to locking out the accelerator pedal simply due to safety reasons.

I.E.> you may be getting accelerator pedal faults.. but it can be any one of these sensors or circuits, wiring harnesses supplying them that can causing your issue.

For all anyone knows, someone may have cut a wiring harness or sensor harness (that includes one of the sensors mentioned above) somewhere for part of the after-treatment systems, or maybe a wire harness somewhere has rubbed thru, gotten corroded and is shorting out, etc. or some other things.

My best guess without seeing the truck would be that some fool might very well have cut or damaged the wires right at the DPF canister when they removed it to hollow it out.. and now the cut wire is shorting itself out.

Second guess would be the coolant level sensor shorting out in the pigtail going to it or the sensor itself?.

Third guess would be a shorted out wire harness going tot he DEF system somewhere that someone screwed with at some point, or at a sharp bend in the harness under the truck somewhere.

Last would be something related to the accel pedal itself.. as one never knows.

-=-= but those are just random guesses based on the limited info provided.

[Luckyjayb]

They took the canisters off. I’ve put the new harness on the oem side of the ecm that includes going to the coolant level sensor. Everything there looked fine. I’m leaning towards the canisters side bc the way he did the work, I wouldn’t be surprised that he cut stuff over there. I’m getting correct voltage on the pedal, coolant sensor, fuel level, and doser control unit. I’ll check the others. Thanks again for the help

[Luckyjayb]

Found and fixed issue. Thanks again

[Rawze]

(04-27-2023 )Luckyjayb Wrote:  Found and fixed issue. Thanks again

Thanks for the update.

Maybe an overview pic of where that is on the truck?.. I am sure other people will likely have that same issue on that make/model truck from the looks of it.

[Luckyjayb]

I’ll get a better picture of where it was at. For a general description, it was running under the front of the TCM mounting bracket and the issue was caused by a torque hose clamp on the hydraulic pump running off the PTO on drivers side of the transmission. This issue was caused by the torque clamp installed by OX Bodies who built the dump bed on it and of course don’t worry about a chassis harness.